Joint replacement at the Hospital for Secial Surgery has shown that the procedure of cementing total hip replacement components in place carries a high risk of infection. Simple preventive measures against infection are essential, including careful identification of patients at special risk, preoperative eradication of all possible foci of infection, and strict observance of high-quality operative technic. The risk of infection and the disastrous consequences of infection when it occurs justifies the use of perioperative bactericidal-antibiotic prophylaxis against gram-positive organisms in patients undergoing total joint replacement. Studies of the 1,350 patients having total hip replacement in a four-year period, with minimal follow-up of two years while on a preventive program of this kind, show that the regimen as used at the Hospital has been effective and devoid of important harmful side effects.